Aluminum Dihydrogen Phosphate Research Articles

Preparation and Properties of Chromium-Free Corrosion-Resistant Coatings for Oriented Silicon Steel

An environmentally friendly chromium-free insulating coating suitable for oriented silicon steel was prepared by using aluminium dihydrogen phosphate, silica sol, water-based resin, sodium tetraborate and graphene aqueous dispersion as main raw materials. The morphology of the insulating coating was characterized by scanning electron microscopy. Corrosion resistance was investigated by neutral salt spray test and electrochemical test. Magnetic properties and surface insulating resistance were measured. The results showed that the surface of the insulating coating was flat; the addition of graphene could effectively improve the corrosion resistance and magnetic properties of the coating. The corrosion rate in the salt spray test was less than 10% after 120h, and the core loss was reduced by 9.57%. The addition of the graphene did not destroy the insulation properties of the coating. The surface insulation resistance per side of the coating was 269.51 Ω⋅mm2.

Study of composition and structure of aluminum phosphate binder

AbstractIn this article, theoretical analysis and different testing techniques were used to study the reaction pathways and synthesized products of phosphoric acid and aluminum hydroxide at different Al/P molar ratios. The results show that: (a) When the molar ratio of phosphoric acid/aluminum hydroxide is 1:3, the reaction will produce stoichiometric aluminum dihydrogen phosphate (Al(H2PO4)3); (b) when Al(OH)3 is excessive, an intermediate, monohydroxy aluminum dihydrogen phospate (HO‐Al‐(H2PO4)2), will appear, which is unstable and will continue to react according to two reaction pathways, one is intramolecular dehydration to form phosphoric acid hydrogen‐dihydrogen aluminum diphosphate (H2PO4)Al(HPO4); the other is intermolecular dehydration cross‐linking to form a polymeric macromolecular aluminum phosphate H‐((HPO4)(H2PO4)Al‐O‐HPO4‐Al(H2PO4)‐O)‐ nH. The ratio of the two pathways is affected by the excess of Al(OH)3. When the excess of Al(OH)3 continues to increase, the ratio of the second reaction path begins to increase and the viscosity of the product gradually increases. Adhesion experiments show that the aluminum dihydrogen phosphate has the best bonding performance benefiting from its lower viscosity.

Properties of inorganic high-temperature adhesive for high-temperature furnace connection

A novel type of inorganic high-temperature adhesive that can be cured at room temperature and applied to a high-temperature furnace was prepared using alumina and micro-silica as materials, liquid aluminum dihydrogen phosphate as a binder, and then sintered at a high temperature. To evaluate the mass ratio of Al2O3:SiO2 and the optimal sintering system, the physical properties of the adhesive after sintering were tested, and the phase and microstructure were characterized. The results revealed that the physical properties of the adhesive at 1300–1600 °C were better at a mass ratio of Al2O3:SiO2 = 5:1. When the sintering temperature was 1300 °C, columnar mullite was formed. At 1500 °C, the adhesive had a high shear strength.

Fabrication of porous silicon carbide ceramics at low temperature using aluminum dihydrogen phosphate as binder

In the present work, phosphate-bonded porous silicon carbide (SiC) ceramics were prepared by using aluminum dihydrogen phosphate as binder. The morphologies, phase composition, microstructures, mechanical strength, porosity and bulk density of the porous ceramics were investigated. It was found that the aluminum dihygrogen phosphate binder bonding method was a novel and low cost process to prepare near net-shape and high strength porous SiC ceramics at low temperature. The bonding mechanism was A type and B type aluminum metaphosphate which formed from aluminum dihygrogen phosphate during heat treatment bonded the SiC particles together to form porous ceramics. With temperature increasing, the phase of B type gradually transformed into A type aluminum metaphosphate, and the transformation was completed at 900 °C. The A type aluminum metaphosphate began to decompose into AlPO4 and P2O5 when the sintered temperature higher than 908 °C. The flexural strength of the porous SiC ceramics reached the maximum at 900 °C and decreased sharply with temperature increasing. The decomposition of A type aluminum metaphosphate made the strength reduce. The bulk density increased with aluminum dihydrogen phosphate content and decreased with temperature, in contrast, the porosity decreased with increasing binder content and temperature.

High-temperature DIC based on aluminium dihydrogen phosphate speckle

Digital image correlation (DIC) method has been widely used for measurement in high temperature environment, where speckle pattern that can withstand high temperature and maintain good stability is required. In this work we develop a simple method to fabricate speckle pattern for high temperature application. The curing temperature of the speckle is controlled under 350 °C to avoid potential damage to the substrate material. The speckle can resist temperature up to 1050 °C for minimum 0.5 h. Three point bending experiment was carried out at 700 °C to test the speckle. Results show that this high temperature speckle exhibits excellent adhesion to the substrate. This non-invasive speckle shows great potential for improving the measurement reliability at high temperature in engineering application.

The Effect of Aluminum Dihydrogen Phosphate on the Enhanced Mechanical Properties of Aluminum Foams

The Effect of Aluminum Dihydrogen Phosphate on the Enhanced Mechanical Properties of Aluminum Foams

Reforming of Poly(3-hydroxybutyrate) to High-Quality Oil with Acidic Phosphates

Poly(3-hydroxybutyrate) (PHB) derived from renewable biological feedstocks is regarded as a potential material for high-quality oil production through weak acid catalysis. PHB can be converted to PHB oil in a single-step reaction catalyzed by aluminum dihydrogen phosphate, and the yield can reach 36.9 wt % at mild reaction conditions (240 °C for 6 h). The hydrogen/carbon ratio and higher heating value of the oil obtained are 1.63 and 42.3 MJ/kg, respectively, which makes it comparable to that of oxygenated commercial gasoline.

Influence of Heat-treatment on High Temperature Young’s Modulus ofthe Inorganic Adhesives with Aluminum Di-hydrogen Phosphate Binder

Influence of Heat-treatment on High Temperature Young’s Modulus ofthe Inorganic Adhesives with Aluminum Di-hydrogen Phosphate Binder

Improvement dielectric and microwave properties of SiCf/SiC-AlPO4 composites prepared by precursor infiltration and pyrolysis process

SiCf/SiC-AlPO4 composites were prepared with dual matrix precursor of polycarbosilane and aluminum dihydrogen phosphate during the PIP process to optimize the dielectric and microwave absorption properties at 8.2–12.4 GHz. Both complex permittivity and tanδ of the composites with simplex SiC and dual SiC-AlPO4 matrix show obvious sensitive behavior with the test frequency. The SiCf/SiC composites exhibit poor reflection loss values owing to the deviation of impedance matching caused by the high complex permittivity. With introduction of AlPO4 into SiCf/SiC composites, the complex permittivity decreased to proper levels and the microwave absorption properties are significantly improved over the whole test frequency ranges. The results indicates that the minimum RL values and bandwidth below −10 dB for the SiCf/SiC-AlPO4 composites reach-22.8 dB and 4.2 GHz, respectively.

Effect of Binders on Preparation of High Temperature Rigid Thermal Insulation Materials

With the development of ultra high temperature rigid heat insulation materials in the space field, it is an important strategic significance to prepare and research insulation materials of 1500°C high temperature. In our paper, the material was achieved through the process of wet suction filter forming and high temperature heat treatment, during which the high temperature alumina fiber was used as main ingredient. The fiber binder directly influences the mechanical and thermal properties of the material, and our samples were prepared using boron carbide and silicon carbide (both), borosilicate glass, alumina sol and aluminum dihydrogen phosphate as binder, respectively. The results show that borosilicate glass was the best one. Coefficient of thermal conductivity at 1000°C, lift strength and plane direction compression strength (10% compression) of the high temperature material were 0.12 W/mK, 0.35 MPa, and 1.1 MPa, respectively.

Preparation of Aluminum Nitride Ceramics by Aqueous Tape Casting

High compacted aluminum nitride (AlN) substrates were prepared by aqueous tape casting. Aluminium dihydrogen phosphate was used to modify AlN particle surface from hydrolysis during casting process. The absolute value of zeta potential for the AlN particle treated by Al(H2PO4)2 was 60mv at pH = 9. The slurry suitable for tape casting was prepared which possessed shear-thinning behavior and appropriate viscosity. The results showed that the green tapes own excellent properties including high bulk density, uniform pore distribution and low porosity. The samples were fired at 1700°C (lower than melting point of Pt) with pressureless sintering process which can be used to fabricate complex device.

Hydrolysis Control of AlN Powders for the Aqueous Processing of Spherical AlN Granules

Spherical granules of aluminum nitride (AlN) with an average particle size of about 50 μm were produced from aqueous suspensions using an AlN powder surface treated against hydrolysis with aluminum dihydrogenphosphate [Al(H2PO4)3]. Two different amounts of Al(H2PO4)3 were tested and the effects of surface treatment and aging time were evaluated by various techniques (XRD, TG‐DTA, zeta potential and pH measurements). The treated powder exhibited antihydrolytic property and good dispersing behavior, enabling the preparation of low‐viscosity and high‐concentration aqueous AlN slurries for freeze granulation. The spherical AlN granules were sintered in a boron nitride (BN) powder bed followed by ultrasonic washing of the AlN granulates/BN mixture to remove BN. The sintered spherical AlN granules present excellent crystallinity and high sphericity as observed from SEM micrographs.

Tensile Strength and Bonding Mechanism of the Mullite Eramic/Ceramic Sample Joined by Phosphate Adhesive

The aluminum phosphate adhesive was prepared by aluminum dihydrogen phosphate and ceramic fillers. The mullite, silica and silicon powders were added as the fillers to improve the mechanical property and high temperature property. The specimens were prepared by joining the mullite ceramic/ceramic by phosphate adhesive. The strengths of the specimens treated at different temperatures were studied. The results indicated that the tensile strength at room temperature was 2.02 MPa, and it reached 5.06 MPa when the specimen was treated at 800°C. The bonding effect and bonding property at high temperature were discussed through the SEM analysis. Besides, the bonding mechanism was also explored.

Effect of Binders on the Properties of Chromia/Alumina Refractory Castables

Refractory castable specimens were prepared using industrial white fused alumina as aggregates, chromium oxide green and ultrafine alumina powder as matrix materials, solid aluminum dihydrogen phosphate (Al(H2PO4)3) or liquid AlPO4 as binder materials. Effect of different binder additions on the propertiSubscript textes of high chromium oxide IGCC refractory castables, such as bulk density, apparent porosity, strength was evaluated and their microstructures were observed by SEM and mercury porosimetry.

Effect of Fly Ash on Thermal and Mechanical Properties of Expanded Perlite Insulation Product

Expanded perlite insulation samples were prepared with expanded perlite as aggregate, aluminum dihydrogen phosphate as binder and fly ash as addition by mixing, molding, drying and calcination. The effects of fly ash mass percentage on the compressive strength, thermal conductivity, moisture content and density of the samples were studied. The results indicated that the combination properties of adding 10 % fly ash were the best among the all samples according to the national standards (GB/T10303-2001) No 350 Qualified of expanded perlite insulation products. Its compressive strength, thermal conductivity, moisture content and density were 0.456 Mpa, 0.08165 W/ (m K), 0.02 mass % and 259 kg/m3, respectively.

Process dependant setting behavior of aqueous gelcast AlN slurries

In this study, AlN powder modified to improve anti-hydrolysis property with aluminum dihydrogen phosphate and phosphoric acid by mechanical milling was applied to prepare M-AlN gelcasting slurry. The effect of various parameters such as concentration of monomer and crosslinker, amount of initiator, solid content and temperature on the idle time was discussed for low-toxic N,N-dimethylacrylamide and N,N′-methylenbisacrylamide (DMAA and MBAM) system. The results suggested that the idle time of M-AlN gelcasting slurries decreased with increasing concentration of monomer and crosslinker, amount of initiator, temperature and the volume fraction of M-AlN. The calculated activation energy of 52.5vol.% M-AlN was 29.46kJ/mol. The M-AlN green body with optimum bulk density and maximum flexural strength was obtained when the amount of APS was 1.2wt.% (on the monomers base), polymerization temperature was 65°C, and polymerization time was 60min for constant DMAA and MBAM (10wt.%, 1wt.% in the premix solution, respectively) in 52.5vol.% M-AlN slurry. The bulk density of AlN sintered ceramic is greater than 3.27g/cm3, which presents relative density value of 99.3% of theoretical.

Preparation and Characterization of A Metal-Based Al/Al<sub>2</sub>O<sub>3</sub> Gradient Coating

An Al/Al2O3 gradient coating applied on a heat-resistant stainless steel was prepared through a slurry process by using aluminum and γ-Al2O3 powders as the transition filler material, alpha alumina as the surface coating material, aluminum dihydrogen phosphate as the binder, and sodium molybdate as the corrosion inhibitor. The effects of heat treatment temperature, adhesive/filler ratio and γ-Al2O3 content on the bonding strength, microhardness and thermal shock resistance were investigated. The crystal phase and microstructure were characterized by XRD and SEM. The results indicated that the composition of the coating changed continuously from surface to coating-substrate interface. The coating could offer high bonding strength and good thermal shock resistance when heat treated at 700°C.

Study on Controlling Effect of Alkali-Silica Reaction by Impregnation Using Aqueous Solutions of Hydrogen Peroxide

The purpose of this study is to grasp of controlling effect of alkali-silica reaction (ASR) by impregnation using hydrogen peroxide 5% aqueous solution (H5), hydrogen peroxide 5% with aluminium dihydrogenphosphate 3% aqueous solution (H5AP3) and lithium nitrite aqueous solution(L) as to impregnant. In this study, the expansion and compressive strength of impregnated and non-impregnated mortars were discussed. The mortars used for impregnation were subjected to various pre-curing conditions. The reactive aggregates used in the mortars were trachyte, glass cullet and andesite. The results obtained are as follows : (1) The reduction of ASR-expansion in the H5-impregnated mortars was influenced by total alkali content, pre-curing condition, impregnant loading and moist curing period of the mortar. (2) The expansion of the impregnant (H5, H5AP3 and L)-impregnated mortars was remarkably smaller than that of the non-impregnated mortar at moist curing eriod from 7 days to 3 years. Especially, the expansion of the H5AP3-impregnated mortar was decreased, as compared with L. (3) The compressive strength of the impregnant (H5, H5AP3 and L)-impregnated mortars was larger than that of the non-impregnated mortar at moist curing period of 3 years. Especially, the compressive strength by impregnation with H5AP3 was increased, as compared with L. (4) From these results, it was recognized that H5AP3 as to impregnant was possessed with controlling effect of ASR and high compressive strength developments, as compared with L.

The role of chemisorbed anions in the aqueous processing of AlN powder

Abstract In the production of ceramics containing AlN it is necessary to prevent the AlN powder from reacting with water. To do that, non-aqueous powder processing is required or water-resistant AlN powders must be used. Alternatively, as in the Hydrolysis Assisted Solidification process, which exploits the hydrolysis of AlN for the solidification of the ceramic suspensions, the hydrolysis has to be prevented at room temperature but initiated at elevated temperatures. In this study the role of the chemisorbed anions in the hydrolysis of the AlN was investigated in order to make the control of the hydrolysis reactions possible. The method for preparing water-resistant, hydrophilic AlN powder using the dispersion of the powder in a solution of aluminium dihydrogen phosphate is also presented. The mechanism leading to the formation of the protective surface layer is proposed and explained. The method was also successfully tested on nanosized AlN powder. This powder was processed in water and sintered to high density.

Protection of AlN powder against hydrolysis using aluminum dihydrogen phosphate

Abstract The hydrolysis of AlN powder in a dilute aqueous suspension was studied by following the pH vs. time in different media. The results show that phosphoric acid is effective in protecting AlN powder at room temperature, whereas at elevated temperatures hydrolysis takes place. When silicic acid or aluminum dihydrogen phosphate were present in the slurry no hydrolysis was observed even at 70°C. Further experiments indicate that by soaking in aluminum dihydrogen phosphate, water-resistant AlN powder can be prepared which will not react with water even after drying and/or redispersion. The protected AlN powder is hydrophilic, which facilitates aqueous powder processing.